Magnetoelectric transducers such as a Hall-effect element, a Hall IC, magnetoresistance element, ferromagnetic resistance element and magnetoresistance IC are widely used as a rotational position detecting sensor of a driving motor of a VTR, floppy (trademark) disk, CD-ROM, DVD, CPU fan etc., and as a switch or encoder in combination with a permanent magnet. As these electronic components shrink, the need for reducing the thickness and footprint of the magnetoelectric transducer has intensified.
In addition, the need for reducing the size and thickness has intensified in the applications to motors that detect the magnetic flux density not only perpendicular to, but also parallel to the mounting surface of the magnetoelectric transducer, because the latter has an advantage of increasing the degree of freedom of the magnetic flux detection position.
One of the most common magnetoelectric transducers is a Hall element fabricated through the process of attaching a magnetoelectric transducer, which is composed of a magneto-sensitive semiconductor thin film including internal electrodes, to a section called an island of a lead frame; of connecting the internal electrodes to the lead frame via metal wires; and of molding the magnetoelectric transducer and part of the lead frame with a resin, followed by other processing such as trimming, forming and electromagnetic test.
FIGS. 44A and 44B show an outline of a rather small example of a conventional Hall element thus fabricated: FIG. 44A is a side view; and FIG. 44B is a plan view. Its height h is 0.8 mm, width w is 1.25 mm, and the length L and width W including the lead frame are 2.1 mm each. The smallest Hall element formed with a lead frame currently on the market has an exterior size with the projected dimensions of 2.5×1.5 mm and the height of 0.6 mm including the lead frame constituting the external electrodes in the package, or an exterior size with the projected dimensions of 2.1×2.1 mm and the height of 0.55 mm. These Hall elements are characterized by being small in height.
A Hall element currently on the market capable of detecting the component of the horizontal magnetic flux density has an exterior size with the projected dimensions of 2.7×2.1 mm and the height of 1.45 mm including the lead frame constituting the external electrodes in the package. It is characterized in that the island of the lead frame, to which the magnetoelectric transducer is attached, is inclined 45° with respect to the mounting surface (see, Japanese utility application laying-open No. 2-033585 (1990)).
However, the foregoing constructions have their limits, particularly to the miniaturization and slimming down of the projected area. Although the magnetoelectric transducer is molded and the mold dimension itself can be reduced to about 1.5×1.5 mm, the lead frame extending out of the mold must be formed, and the extended portion imposes a limit to the miniaturization. In addition, the loop height of the metal wires also hampers the slimming down. Although a method is known of erecting the island of the lead frame vertically to detect the horizontal magnetic flux density, it must protrude the lead frame from the upper section of the mold and bend. Thus, the length of the island of the lead frame and the part of the lead frame at the upper section of the mold hamper the slimming down.
The present invention is implemented from the idea to reduce the dimensions of the magnetoelectric transducer in its entirety including the mounting electrodes to about the mold dimensions without using the metal wires.
The present invention is implemented in view of the foregoing conditions. Therefore an object of the present invention is to provide a magnetoelectric transducer and its manufacturing method including a ultrathin, small-footprint, compact magnetoelectric transducer, and a ultrathin, compact magnetoelectric transducer with a vertical mounting type capable of detecting the magnetic flux density differing by 90° in the direction.